Anode cooling for rectifiers



Aug. 9, 1932. E. B. SHAND ANODE COOLING FOR REGTIFIERS Filed March 20. 1930 r lNVENTOR fire/5 5/70/74 ATTORNEY Patented Aug. 9, 1932 V v iusrrsa stares ,PATs T QFFICE ERROL B.. SHAND, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTINGHONSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA 'ANODE COOLING FOR RECTIFIERS Applicationfiled March 20, 1930. Serial No. 437,403.

My invention relates to a cooling system for electrodes and particularly to a closed cooling system for the anodes of mercury; arc rectifiers. Prior to my invention, considerable difliculty Was experienced in properly anodes have been surrounded by shields, as

these shields have materially reduced the rate of radiation.

The second system of anode-cooling comprised the use of radiators in heat-conducting relation to the bodies of the anodes in addition to the radiation fromthe anode surfaces. Under the present systems of ratings,

the largest practical radiator Wlll dissipate about one-half of the heat required to be dissipated from a particular anode, and there has been considerable difficulty in securing heat transfer from the anode surface to the radiator. Furthermore, there has been considerable difiiculty in selecting a medium to conductor carry the heat from the interior, of the anode to the radiator per se. The rate at Which heat is carried by conduction through metal has been entirely too lOW. When the convectionof a liquid is used to conduct the heat, considerable difliculty has been experienced in finding a suitable liquid medium. If ater Was used, excessive evaporation took place, or, if oil Was used, the heat Was sufiicient to cause carbonization of the oil, and the deposits of sludge in theinterior of the anode, rapidly disabled the system.

' The third system heretofore used for anode-cooling has depended on the circulation of the liquid .medium through cavities in the anode. lPrior-to my invention, several difiiculties have been met in this system. If

Water was used as a cooling medium the slight conductivity of Water produced a serious msulatlng problem for the anodes. Furthermore, in many cases, the anodes Were different in interior structure. Consequently, the rate of flow through the was modified by the interior structure of the anodes. If oil Was used, there was no satis various anodes.

factory method of cooling the oil to a degree 7 sufficient to prevent sludging in the anodes.

By the use of my invention, the disadvantages of this third system have been largely avoided, primarily by providing a method of, and means for, satisfactorily cooling the medium circulated through the anodes. Also, I have eliminated thetroubles of differential flow through various anodes by connecting the anodes in series so that the circulating fluid must flow through all anodes alike. In

order to obviate the difiiculties of insulation,

Ipreferably make use of an insulating fluid,

such as an oil having a high sludge point, as acooling medium. V g I l/Vith the foregoing objects and advantages in View, and others Which Will be apparent,

my invention consists inthe methods and combinations hereinafter described and claimed, and illustrated in the accompanylng drawmg, wherein Figurel' is a vertical sectional elevationof a rectifierembodying my invention; and

F i g. 2 is a top plan View showing the manner of connecting myimproved cooling sys tem to the anodes of a rectifier. r

The apparatus disclosed in the drawing comprises a rectifier having an enclosing metal tank or container 1, infwhich is lo.-j

cated a vaporizable reconstructing cathode 2 of mercury and a plurality of anodes. The bottom of the tank is preferably of sloping formation to'assist the return of the cathode,

material.

Surroundlng the tank or container 1s a cooling jacket 4: through Which is circulated a suitable cooling medium, usually ater.

The jacket, is preferably providedv With a v flat bottom, thus providing an enlarged space between the bottom of the tank and the jacket. Locatedwithin this enlarged space be- Y tween the tank and the jacket, and immersed in the cooling medium, is a coil 5 which car ries a cooling medium for: the anodes, as will subsequently be described.

Each anode comprises an enlarged hollow thick-wall metal head 6 and a tubular metal body 7 integrally connected. Around the tubular body is located any desired insulating material 8 to insulate the anode from the rectifier tank 1.

Extending into the tubular body 7, and

into proximity to the integral anode-head 6, is a tube 9, preferably constructed of a molded artificial resin or other insulatingmaterial, through which oil or other cool ing "mediummay be introduced into the anode. v

This cooling medium, being introduced into the anode at the vicinity .of the head '6, will abstract heat from the head and will flow back outside of the central'tube 9 but through the tubular anode body 7 carrying the heat to an outlet chamber 10 spaced from the base of the anode by an insulating collar 11, The insulating collar 11, in conjunction with the insulating tube 9, provides an inletpassage and insulates the cooling system from the high potential of the anode so that the'cooling system may be at tank potential, or any other desired potential. The insulation of the cooling system is further maintained by the use of an insulating fluid, such as oil, for the cooling liquid. The use of an insulated cooling system'p'ermits the use of metallic tubing to carry the cooling fluid and allows long periods of'use withoutservicing of'the cooling system, such as was required with the rubber or fibrous tubing heretofore employed. "Each of the working anodes of the rectifier is of similar construction.

In order to provide a closedor series system for the cooling of the anodes, the outlet 10 of one anode is-connected by a tubular means 12 to the inlet 90f the next following anode H I a j The anodepassages,having all beengconnectedin series, the outlet 10 from the last anode is connected to the cooling coil 5 which is immersed in the cooling system of the rectifier tank, as indicated at 15 in Fig. 2.

- A pump-17 is inserted between the outlet .10 of last anode and the inlet 15 of the cool- -ing coil 5. This pump 17 should impart such velocity to the oil that all parts of the oil will be in constant circulation without eddies or still pockets. Also, this; velocity should be such that the maximum temperature of the oil should be well below the sludge'point of the oil. VVhile there will be a possible maximum temperature diiference in the oil 5 I of about 15 C. between the first and the last anodes, this" will make no appreciable difference in the anode cooling because of lithe great difference in temperature between the oil and the anode heat. "Also, since the anodes do not cool immediately upon ces sation of operation of the rectifiers, it is V necessary that the circulation of cooling oil be maintained for several minutes after shutdown of the rectifier proper.

The operation of my device is as follows:

When a rectifier is placed in operation, the pump 17 is set in motion. This pump causes acirculation of oil through the cooling coil 5 and the series-connected anode cavities. This oil, after being cooled in the cooling coil 5, is again repumped through the anodes. V

In order to provide for the expansion caused by the heating of the oil, it is necessary topr ovide an expansion chamber or reservoir connected to the closed circulating system. This may be a reservoir 19 placed above the cooling system or it may be sylphon arrangement, not shown, attached to 'anypoint of the system.

In order to prevent sludging of the oil after the cessation of operatlon of the rectlfier, it is necessary that the motor driving the pump shall be continued in operation for a considerable period after such cessation, or, at least, for such period as 15 necessary to tions as to the ermissible arcin -surface temperatures of'the anode heads to point which is far removed from the other design limitations which affect present metal-tank, mercury-arc rectifier des1gns, so thatanode cooling is no longer a factor in determining" the'maxlmum permissible loading of a moifier.

Although I have shown and described a certain specific embodiment of my invention,

I am fully aware that many'modifications' thereof are possible. My invention,- therefore, is not to be restricted except insofar as is necessitated by the prior art and by spirit of the appended claims. 7

I claim as my invention: r r e y 1. An anode-cooling system for a metaltank rectifier comprising a tank, a water jacket surrounding the tank, an enlarged space at the bottom ofthe jacket and between the jacket and the tank, a coil of pipe in the enlarged space, a 'pluralityof anodes for the the rectifier, each anode having a longitudinl' cavity therein, an outlet chamber at the end of the cavity, and a tube extending through'the outlet chamber and into'the cavity, a tube ex tending from the outlet chamberof .one an ode to the inlet tube of the next so that the anode cavities are connected in series, the

outlet chamber of the last anode being' connected to the inlet of the first through the coil in the water jacket to make a closed system, an insulating anode-cooling fluid in the system, means for circulating the fluid through the system, and an expansion chamber connected to the system.

2. An anode-cooling system for a mercuryarc rectifier comprising a container, a jacket surrounding the container to provide a space between the container andthe jacket for a cooling liquid for the rectifier, a plu' rality of anodes for the rectifier, each an.- ode having a cavity therein, an inlet tube extending therein to introduce cooling fluid, and an outlet from said cavity for the escape of cooling fluid, a cooling coil in the" space between the rectifier casing and the jacket, one end of said cooling coil being connected to an anode inlet tube and the other end of said cooling coil being connected to an anode outlet, and means for forcing the circulation of cooling fluid.

3. An anode-cooling system for a metaltank rectifier comprising a casing, means for circulating water about the rectifier casing, a plurality of anodes in the rectifier, each anode having a longitudinally extending passage therein, inlet means for introducing a cooling fluid into the anode, and an outlet for the cooling fluid, said inlet and outlet being insulated from the anode, means for conducting the fluid from the outlet or" one anode to the inlet of the next so that all are con nected in' tandem, means for causing the anode-cooling-fluid to be cooled by the water circulated about the casing, and means for causing a circulation of the anode-cooling fluid.

4. An anode-cooling system for a rectifier comprising a container, a water jacket for the container, a plurality of anodes in said rectifier, eachanode having a longitudinal cavity extending from the top to the head thereof, means for introducing cooling fluid into the cavity, and means for discharging the fluid from the cavity, means for conducting the fluid from the outlet of one anode to the inlet of the next, a coil placed within the water jacket, means for connecting the coil in the cooling system for the anodes, means for causing a circulation of the anode-cooling fluid in said system and means for permitting expansion of the cooling fluid.

5. A cooling system for the anodes of a rectifier comprising a cooling jacket for the rectifier, a plurality of anodes in the rectifier, each of the anodes having a longitudinal passage therein, an inlet pipe extending into each of the passages for a major portion of the length thereof, an outlet member for each passage, means for connecting the passages in the several anodes into a continuous system, means within the cooling jacket and contained in the continuous system for cool-' cooling fluid enclosed in said continuous system, and means for circulating the cooling fluid through said system.

6. An anode-cooling system for a metaltank mercury-arc rectifier comprising a plu- 4 rality of anodes for the rectifier, each anode having a thick-wall head and a tubular body, an'insulating tube extending into said tubular body, a supply tube for cooling fluid connected to said insulating tube, an exhaust tube connected to the base of the anode, an insulating collar between the exhaust tube and the body of the anode, an insulating cooling fluid in the system, means for circulating the cooling fluid, and means for cooling the circulatory fluid.

7. A cooling system for the anodes of a metal-tank mercury-arc rectifier comprising a metal tank, a cooling acket surrounding the tank, a plurality of anodes in said tank, each of said anodes comprising a hollow head having a wall thickness greater than two inchesv and a tubular stem integrally connected with said head, the hollow in said head being so In testimony whereof, I have hereunto subscribed my name this 5th day of March, 1930. ERROL B. SHAND.

ing the anode-cooling fluid, an insulating 

